A 390-GHz Outphasing Transmitter in 28-nm CMOS

Abstract

This paper presents a 390 GHz Outphasing Transmitter in 28 nm CMOS. Generating higher order modulation schemes at THz frequencies is very challenging due to the essential nonlinear elements needed to generate signals above Fmax. Harmonic outphasing could provide an answer for transmitters which use a multiplier last topology. The topology addresses both amplitude and phase distortion issues, which are inherent for multiplier-last architectures. The 5-bit on-chip outphasing symbol generator is sufficient to generate modulation schemes from OOK to 16-STAR QAM. The chip is packaged with a direct chip-towaveguide interface thus providing easy RF access through the WR2.2 waveguide interface. The transmitter can deliver a peak measured output power of −16 dBm with a 3 dB IF bandwidth of 16.5 GHz. The maximum achieved data rate was 6 Gbps.

A Bi-Directional 300-GHz-Band Phased-Array Transceiver in 65-nm CMOS With Outphasing Transmitting Mode and LO Emission Cancellation

“…The outphasing technique is usually applied to power amplifier systems to improve their efficiency by driving the amplifier at higher output power levels [60]- [62]. It was also used with frequency multipliers to provide higher efficiency as in [35]. In our design, we adopt the outphasing architecture using the passive subharmonic mixers to improve the average output power of the TX at the 300-GHz band.…”

“…As a result, the CMOS amplification is not normally used for systems that operate at frequencies above 170 GHz [19]- [22]. Although several 300-GHz-band CMOS amplifiers have been demonstrated lately [23]- [26], their characteristics are still not reliable for wideband 300-GHz-band wireless TRXs, causing the dominance of the mixer-last (or multiplier-last) transmitter (TX), mixer-first receiver (RX) architecture in the recent works [27]- [35]. This architecture suffers from the limited output power, high noise figure, and the LO feedthrough (LOFT) radiation from both TX and RX.…”

“…This architecture suffers from the limited output power, high noise figure, and the LO feedthrough (LOFT) radiation from both TX and RX. The output power issue was mainly faced by using frequency multipliers instead of mixers [27], [29], [30], [32], [35].…”

64QAM wireless link with 300GHz InP-CMOS hybrid transceiver

“…CMOS amplifiers operating around 300GHz were introduced in the literature despite the low f max as in [19,20], but a reliable wideband operation is yet to be demonstrated. Many works sacrificed the presence of an amplifier to realize the 300GHz wireless link using CMOS [21,22,23,24,25,26,27,28,29,30]. The resulting mixer-last transmitter, mixer-first receiver system has very severe mixer linearity requirements, causing the overall system complexity to increase in order to get a reliable high data rate link.…”